The chemical composition of the essential oil obtained from the aerial parts of Z. clinopodioides subsp. rigida (BOISS.) RECH. f. was analysed by GC and GC-MS. Thirty-one constituents accounting to 99.5% of the total oil were identified. Oxygenated monoterpenes (93.3%) were the predominant portion of the oil with pulegone (45.8%), piperitenone (17.4%), p-menth-3-en-8-ol (12.5%) and thymol (8.0%) as the main constituents. Antibacterial activity of the oil and its two main compounds and various extracts of plant were tested against seven Gram-(+) or Gram-(-) bacteria. It was found that the oil and MeOH extract (M) exhibited interesting antibacterial activity. The samples were also subjected to screening for their possible antioxidant activity by using 2,2-diphenyl-1-picrazylhydrazyl (DPPH) assay. The free radical scavenging activity of MeOH extract (M) was superior to all other extracts (IC50=30.7 microg/ml), while the oil was less effective.
Due to the rise in antibiotic resistance, new sources of anti-H. pylori drugs are needed. The use of medicinal plants and/or their chemical components may have potential benefit in eradicating such problems.
Pseudomonas aeruginosa is the predominant respiratory pathogen in patients with cystic fibrosis, but its Mechanism of persisting in pulmonary secretions is poorly understood. We observed that three nonmucoid cystic fibrosis P. aeruginosa strains were phagocytized and one strain resisted phagocytosis by human polymorphonuclear leukocytes in the absence of serum. Phagocytosis was assessed by luminol-enhanced chemiluminescence, inspection of stained smears, bactericidal assay, reduction of nitroblue tetrazolium dye, and electron microscopy. Phagocytosis, determined by visual inspection, occurred at 35°C but not at 4°C. Nonopsonic phagocytosis was inhibited most efficiently by D-mannose, mannose-containing saccharides, and D-fructose. Opsonin-dependent phagocytosis of P. aeruginosa and of zymosan was not markedly inhibited by mannose, suggesting different leukocyte receptors for nonopsonic and opsonic phagocytosis. Pseudomonas aeruginosa has lately emerged as an important pathogen in individuals with impairment of host defenses due to cystic fibrosis, thermal injury, and malignant tumors (21, 25). Other investigators have defined the opsonic requirements for phagocytosis and killing of P. aeruginosa by human polymorphonuclear leukocytes (PMN) (2, 16, 28) and by macrophages (20) and have attempted to explain why strains from patients with cystic fibrosis resist phagocytosis (1, 23). In studies with cystic fibrosis P. aeruginosa isolates, we observed that phagocytosis occurred in the absence of serum and was inhibited by certain sugars. Observations on the nonopsonic phagocytosis of P. aeruginosa by human PMN form the basis of this report. MATERIALS AND METHODS Bacterial strains. Mucoid strains of P. aeruginosa were cultured from the sputum of patients with cystic fibrosis and identified by oxidase reaction, growth at 42°C, pigment production, and the API 20E system (Analytab Products, Inc., Plainville, N.Y.). They were serotyped by using the Difco typing system (Difco Laboratories, Detroit, Mich.). Strain P-1 (type 9/10) was from the University of Minnesota Hospitals, Minneapolis. Strains C-1 (type 6/9/10), C-46 (type 9/10), and C-96 (nontypable) were from British Columbia's Children's Hospital, Vancouver. Nonmucoid spontaneous laboratory revertants were frozen at-70°C in Mueller-Hinton broth with 8% dimethyl sulfoxide and used as seeds for each experiment. For all experiments, nonmucoid revertant bacteria were grown on Mueller-Hinton agar at 35°C for 18 h, removed with a sterile swab, washed thrice in phos
The exopolysaccharide (alginate) of mucoid strains ofPseudomonas aeruginosa is believed to be an important virulence factor. The ability of an alginate-depolymerizing enzyme (alginase) to modify the polymorphonuclear leukocyte (PMN)-directed and antibiotic-mediated phagocytosis and killing of mucoid P. aeruginosa was studied both in vitro and in vivo. In vitro, pretreatment of a mucoid P. aeruginosa strain (144MR) resulted in a significant enhancement of PMN phagocytosis and killing of the organism (P < 0.05), to levels similar to that observed with its nonmucoid mate, strain 144NM. Moreover, alginase treatment of the mucoid strain 144MR caused a substantial removal of bacterial cell surface alginate as assessed by immunofluorescence staining with a murine monoclonal antialginate antibody. The experimental endocarditis model was used to evaluate the in vivo effect of alginase in modifying the course of a deep-seated pseudomonal infection caused by mucoid strain 144MR. In right-sided endocarditis, in which PMNs normally mediate spontaneous clearance of the organism from cardiac vegetations (Chemotherapy 35:278-288, 1989), the presence of the alginate exopolysaccharide on strain 144MR was associated with an inability to reduce intravegetation pseudomonal counts over a 13-day postinfection period; in contrast, right-sided vegetations infected with the nonmucoid strain 144NM underwent significant reductions in bacterial densities over this same time (P < 0.05). Administration of alginase intravenously (i.v.) (750 enzyme units per day for 7 days) to animals with right-sided endocarditis caused by the mucoid strain 144MR was associated with a significant reduction in intravegetation pseudomonal counts (P < 0.05), to levels similar to that seen with endocarditis caused by the nonmucoid strain. In left-sided endocarditis caused by mucoid strain 144MR, animals received either no therapy, amikacin (20 or 40 mg/kg twice a day for 7 or 14 days), or amikacin plus alginase (750 U/day [i.v.]). The coadministration of alginase for 14 days with the higher-dose amikacin regimen rendered more left-sided vegetations culture negative than those in animals receiving the antibiotic alone for 7 or 14 days (P = 0.001 and 0.056, respectively). These salutary effects of alginase in vivo were paralleled by the ability of the enzyme to remove the exopolysaccharide from the surface of mucoid pseudomonal cells within cardiac vegetations, as assessed by transmission electron microscopy. Collectively these data indicate that the alginate exopolysaccharide was an important factor in inhibiting clearance of mucoid pseudomonal organisms from vegetations by both PMN-directed and antibiotic-mediated processes; the coadministration of alginase in vivo enhanced the clearances of mucoid pseudomonal strains from such infection foci.
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